This invention relates to a driving method for use in driving a plasma display panel (PDP).
In general, a PDP of the type described has various advantages such that a thin structure, a high contrast ratio, and a high speed response can be achieved and a large size screen can be realized without flickering. In addition, multi-color displays can also be accomplished by the PDP with a luminescent material of a self-emission type. Therefore, it is a recent trend that the PDP has been widely used in various fields related to computers and the like.
Conventionally, a PDP of the type described is classified by driving methods into an A. C. type and a D. C. type. Herein, the A. C. type PDP has electrodes covered with a dielectric film and a protection film and is indirectly operated in the state of an A. C. discharge while the D. C. type PDP has electrodes exposed to discharge spaces and is operated in the state of a D. C. discharge.
Moreover, the A. C. type PDP is further divided into a double-electrode opposing type having two opposed electrodes, a surface-discharge type having two electrodes on the same surface, and a triple-electrode type developed from both types. Recent attention has been mainly focused on the triple-electrode type PDP.
Such a D. C. type or an A. C. type PDP tends to adopt a driving method which uses a memory effect of each discharge cell and which may be called a memory drive method. With this method, it is known in the art that a high average luminance can be accomplished by the memory drive method because light emission lasts even for a non-scanning period.
Herein, a conventional driving method will be described in connection with the A. C. type PDP which has three electrodes. As known in the art, such a PDP has a plurality of scanning electrodes arranged in parallel with one another in one direction, a plurality of sustain electrodes adjacent to and parallel with the scanning electrodes, and a plurality of data electrodes perpendicular to the scanning electrodes on a surface different from the scanning and the sustain electrodes. With this structure, cells are defined at cross points between the scanning electrodes and the data electrodes. Thus, the cells are arranged in rows and columns on a surface of the PDP.
In the conventional driving method, the cells are scanned by successively selecting the scanning electrodes and are put into lightened states by selecting the data electrodes so as to cause discharges to occur between the selected scanning electrodes and the selected data electrodes. As a result, an image is displayed on the PDP at every field.
As one of the conventional driving methods, so-called a sub-field driving method is known which divides each field into first through n-th sub-fields, where n is a positive integer greater than unity. With this method, all of the cells are scanned in every sub-field and are discharged each time when the corresponding data electrodes are selected. Under the circumstances, the cells are repeatedly discharged within each field and exhibit a luminance or brightness in dependency upon repetition times of the discharges of each cell within the respective sub-fields.
Heretofore, a technique of priming or provisional discharges is used in the PDP before usual discharges, namely, normal discharges are started so as to realize a high speed operation. According to this technique, the priming discharges are caused to occur in all the cells at every sub-field of the field.
Although such priming discharges facilitate the following normal discharges in the next sub-field, non-lightened cells are also undesirably influenced by the priming discharges. This is because the priming discharges are carried out regardless of whether or not the cells are lightened. Therefore, a contrast ratio is seriously degraded in a dark region of an image displayed on the PDP.
In Japanese Unexamined Publication No. Hei 4-280289, namely, 280280/1992 (will be referred to as Reference 1), a screen is divided into a plurality of regions in each of which the priming discharges are individually discharged. However, no consideration is made at all in Reference 1 about a reduction of the contrast ratio in the dark region.
In Japanese Unexamined Publication No. Hei 8-221036 (221036/1996) (will be referred to as Reference 2), disclosure is made about avoiding a reduction of the contrast ratio. In Reference 2, proposals have been offered in connection with a method of counting display data numbers in each sub-field and generating priming discharges in cells which have a lot of data numbers and a method of generating priming discharges with reference to a previous sub-field. With these methods, the priming discharges are often caused to occur in non-lightened cells which have the data number 0. When such non-lightened cells are undesirably influenced by the priming discharges, the luminance in such cells never become equal to zero. In addition, no teaching is made in Reference 2 about avoiding diffusion of charged particles to non-lightened cells.
It is an object of this invention to provide a method of driving a PDP without a reduction of a contrast ratio in a dark region.
It is another object of this invention to provide a method of the type described, which can use a wide range of an operation voltage.
It is still another object of this invention to provide a method of the type described, which can improve a write-in characteristic.
According to an aspect of this invention, a method is for use in driving a plasma display panel (PDP) to display an image at every field which is divisible into first through n-th sub-fields, where n is a positive integer greater than unity. The PDP comprises a plurality of scanning electrodes, a plurality of data electrodes, and a plurality of cells located at cross points between the scanning electrodes and the data electrodes. The method comprises the steps of determining the first sub-field and the second through the n-th sub-fields as a priming sub-field and display sub-fields, respectively, causing priming discharges to occur at selected ones of the cells within the first sub-field, and causing display discharges to occur at the selected cells within the second through the n-th sub-fields to display the image.
According to another aspect of this invention, a method is for use in driving a plasma display panel (PDP) to display an image at every field which is divisible into first through n-th sub-fields, where n is a positive integer greater than unity. The PDP comprises a plurality of first electrodes, a plurality of second electrodes intersecting the first electrodes, a plurality of third electrodes parallel with the first electrodes, and a plurality of cells located at cross points between the first electrodes and the second electrodes. The method comprises the steps of determining the first sub-field and the second through the n-th sub-fields as a priming sub-field and display sub-fields, respectively, supplying the third electrodes with sub-priming pulses in the first sub-field. supplying the first and the second electrodes with first and second priming pulses, respectively, with the sub-priming pulses in the first sub-field to cause priming discharges to occur at selected ones of the cells within the first sub-field, and causing display discharges to occur at the selected cells within the second through the n-th sub-fields to display the image.
According to another aspect of this invention, a method is for use in driving a plasma display panel (PDP) to display an image at every field which is divisible into first through n-th sub-fields, where n is a positive integer greater than unity. The PDP comprises a plurality of first electrodes, a plurality of second electrodes intersecting the first electrodes, a plurality of third electrodes parallel with the first electrodes, and a plurality of cells located at cross points between the first electrodes and the second electrodes. The method comprises the steps of determining the first sub-field and the second through the n-th sub-fields as a priming sub-field and display sub-fields, respectively, successively supplying the first electrodes with first priming pulses partially overlapping with one another in the first sub-field, successively supplying the second electrodes with second priming pulses synchronized with the first priming pulses in the first sub-field to cause priming discharges to occur in selected ones of the cells determined by the first and the second electrodes and peripheral ones of the cells adjacent to the selected cells, and causing display discharges to occur at the selected cells within the second through the n-th sub-fields to display the image.